Assembly for moving heavy objects

ABSTRACT

An assembly for movement of heavy objects is made up of a unit which can be arranged on the fork of a forklift truck and which has a sliding plane (5) and an operating mechanism (8) designed so as to be able to pull or push an object onto or respectively out from the sliding plane and along the latter. The operating mechanism has, in parallel tracks below the sliding plane, longitudinally displaceable drive elements (9, 10) and, arranged on these, carriers (13) which project above the sliding plane and transmit force to the object.

FIELD OF THE INVENTION

The present invention relates to an assembly that is useful inindustrial premises for conveying heavy objects such as press tools,workpieces and the like, for facilitating the movement of the objectsfrom one to another of a number of supports such as a loading stool, ashelf or a table in a press or other machine tool.

The invention relates more particularly to the known type of suchassemblies that comprises a unit which is arranged to be placed on thefork or a forklift truck and which, when placed on the fork, forms asliding surface that extends in the longitudinal direction of the forktines, for carrying the objects, and which unit comprises an operatingmechanism designed to be able to pull onto the sliding surface an objectsituated on a first supporting surface that is level with the slidingsurface, to slide the object along the sliding surface towards its innerend to a conveying position and, in the opposite direction, to push theobject from the conveying position, sliding along the surface and pastits outer end onto a second supporting surface which also, uponadjustment in height of the fork, is level with the sliding surface.

BACKGROUND OF THE INVENTION

In a commercially available assembly of this type the operatingmechanism consists of two parallel, electrically driven ball screwswhich have their ball nuts connected to a toggle on the top side of thesliding surface. The toggle consists of a couple of links which canoperate in two different relative positions, of which one, when thelinks are pulled together and stand at an angle to the sliding surface,can be used when, for example, a press tool is moved while it is restingon the sliding surface, while the second relative position, when thetoggle is adjusted so that the links are in line with each other andwith the sliding surface and thus can reach outside the sliding surface,is the one which has to be used for the tool to be transferred from thesliding surface to a press table or other support, just as whentransferring in the opposite direction onto the sliding surface.

With each such transfer of large and heavy objects from or to a supportthe toggle has to be adjusted between these two working positions, andthis adjustment requires that the ball screws operate while the objectis lying still on the sliding surface. This discontinuous working mannerdelays and complicates the handling of the objects. Also, because of thedesign of the operating mechanism, the assembly is unnecessarilyexpensive.

It is also previously known to incorporate, in a forklift truck, ahydraulic-mechanical operating mechanism for handling press tools andthe like. The forklift truck is made specially for the purpose and socannot be used generally as a goods and transport vehicle. It thereforeremains unused throughout the period which elapses in a plant betweentool changes and similar operations that can be carried out with thetruck. In addition to the fact that it is uneconomical, this forklifttruck has the disadvantage that its operating mechanism operateshydraulically, i.e. it does not permit handling of heavy objects, suchas are found in the engineering industry, of 1 meter or more.

SUMMARY OF THE INVENTION

The aim of the invention is to make use of the great transport economyadvantages which lie in an accessory for use in moving objects in anindustrial plant by means of a forklift truck, constituting a unit whichcan be placed on the forklift truck at the times when such movement isto be carried out, but which, in the interim, can be kept separate fromthe forklift truck so that the truck can be used for other conveyingwork arising in the industrial plant. The invention seeks to incorporatethis advantage into an assembly suitable for this purpose which, as anaccessory to a forklift truck, is made up of simple mechanicalcomponents, is easy and inexpensive to manufacture, and is simple tooperate.

At the same time the invention seeks to eliminate the disadvantageswhich are found in the above mentioned prior assemblies of this typewherein a continuous displacement movement is not possible.

These aims are achieved, according to the primary characterizingfeatures of the invention, by an operating mechanism comprising a pairof chains each of which is arranged to be displaced in the longitudinaldirection of the fork tines and parallel to the other chain by means ofa sprocket wheel located at the rear end of the sliding surface andwhich forms one operative and one inoperative chain stretch, each havinga free end, the operative chain stretch being lengthwise slidablyconfined in a straight groove extending from the upper part of thesprocket wheel to the front end of the sliding surface so that saidoperative stretch of each chain can transmit both pulling and pushingforces for manoeuvring the objects respectively to and from theconveying position, while the inoperative chain stretch runs in a guideextending from the lower part of the sprocket wheel, and carrierelements which are attached to the ends of the operative chain stretchesproject up from said grooves, above the sliding surface, and transmitthe maneuvering force from the ends of the operative chain stretches.

Compared with the previously known designs an assembly having thefeatures mentioned here is considerably simpler and less expensive. Byvirtue of the fact that the chains are designed to effect displacementthrough the entire distance that an object is to be pulled or pushedduring its loading onto the truck or unloading from the same,respectively, the assembly is able to effect every such displacementwithout any interruption, which speeds up the handling and facilitatesthe work for the truck operator. An essential design simplificationcompared with the know technology is also achieved by the fact that theoperative chain stretches can transmit both pulling and pushing force.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in greater detail hereinafter withreference to the attached drawing in which:

FIG. 1 is a perspective view illustrating the assembly according to theinvention in use at a press.

FIG. 2 shows, again in perspective, the assembly according to theinvention, of which smaller parts are cut away.

FIG. 3 is a longitudinal section of the assembly along the line III--IIIin FIG. 4, which is a plan view.

FIGS. 5 and 6 are cross-sections along the lines V--V and VI--VIrespectively in FIG. 4.

BACKGROUND OF THE PREFERRED EMBODIMENT

As assembly according to the invention each be used in many differenttypes of industries where movement of heavy and large objects, such astools, castings or other work-pieces commonly takes place, and where aforklift truck is used for such movements. In a typical case, as isillustrated in FIG. 1, it may be a question, in an engineering workshopor other idustrial plant, of moving a press tool A to or from a supportB which, in the use example shown, is a press table of an eccentricpress C.

By means of a forklift truck D, partially shown in the figure, the toolA is thus conveyed, carried by the fork E of the truck, between thepress and another support which can be a storage shelf or a loadingbench.

As is known, the forklift truck D, when used for conveying of this type,has an accessory 1 of a type that is generally known, comprising a unitwhich can be placed on the fork tines E of the truck when the latter isto be used for moving press tools or other heavy objects but which,during the time when such movements do not take place, can be keptseparate from the truck so that the latter can be used for otherconveying work arising in the plant.

The assembly 1 is built on a substantially plate-shaped frame ofsheet-metal forming two leg parts 2, 3 which project from a motor part 4and which extend parallel to each other in the same relative position asthe fork tines E. When the assembly is in use, the leg parts thus cometo rest on the fork tines, as is best seen from FIG. 6, and the legparts together define a platform, the top surface portions of whichconstitute a sliding surface 5 on which the tool A is to be carried. Thesliding surface extends in the longitudinal direction of the tines fromthe motor part 4, where the sliding surface has its rear end 6, alongthe entire length of the forks, so that the front end 7 of the slidingsurface is at or slightly in front of the front edge F or the tines.

The said end 6 of the sliding surface normally corresponds to theposition which the truck driver wishes the tool A to assume while he isdriving the latter from or to the press table B, and, in order to beable to move the object along the sliding surface 5, in towards theconveying position or outwards from the latter, the assembly has, as isknown, an operating mechanism of a generally known type which isgenerally designated by 8 in the drawing.

The operating mechanism operates electromechanically and according tothe invention comprises a pair of drive elements 9, 10 which arelongitudinally displaceable in the assembly and which preferably consistof roller chains, for example of the type used in bicycles.

The drive elements 9, 10 run in parallel tracks 11 and 12 respectively,preferably located on the inside of the leg parts 2 and 3 respectively,i.e. in the space between the fork tines E, and the tracks extend belowand along the sliding surface 5 from its outer or front end 7 to theinner or rear end 6. In this case the drive elements are to be designedso that they can be longitudinally displaced in the tracks through thesame distance as the tool A is displaced when it is to be transferredfrom its operative position on the press table B to its conveyingposition at the rear of the sliding surface 5, or when it is to bepushed in the opposite direction and delivered onto the press table or astorage shelf.

The operating mechanism 8 moreover comprises carrier elements 13 whichare attached to the drive elements 9, 10 and follow these inlongitudinal movement along the entire length designated by L in FIG. 3.The carrier elements project up from the drive elements above thesliding surface 5 so that they can act on the inward side of the tool Aand transmit to it the horizontal force which is required for itsdisplacement.

In the illustrated embodiment of the invention each leg part 2, 3, ismade integral with a U-shaped rail 14, 15. The rails, which define thetracks in which the drive elements 9, 10 are operative, are shown hereto follow the inner side of the respective fork tines E when theassembly is in place on the truck. Depending on the relative distancebetween the tines and the width of the objects which are to be conveyed,the rails can have another position, such as on the outside oralternatively top side of the tines. In the case of such greater lateralspacing, it may be advantageous to arrange a third drive elementoperating in the centre of the assembly between the two tines.

As can best be seen from FIGS. 2 and 6, the leg parts 2, 3 haveprojections 16 which are directed downwards and are made by punching andbending a square piece of the sheet-metal material. The projections areintended to fit into the recesses G which are standard for forklifttrucks, and the projections thus provide, together with the rails 14,15, a defined working position for the assembly when it is set down fromabove onto the tines, and without other holding means being required.

Incorporated in the rails 14, 15 are profiles which form continuouslongitudinal grooves 17 for the drive elements or chains 9, 10. Theprofiles can be made up of three parts held together in the rails or, asshown in FIG. 6, can be designed in a single piece fixed with screws 18.The material of the profiles is expediently Teflon or some othermaterial which provides low friction with respect to the drive elementsand has good wear resistance. As appears from the figure, each profileforms a pair of opposite groove walls 19 and 20 which, in the transversedirection and vertical direction, respectively, surround and guide adrive element 9, 10 inserted in the groove 17. The drive element is thusconfined by the groove to linear displacement, even when it is subjectedto a pressure load in the longitudinal direction. According to a primarycharacteristic feature of the invention the drive element can thereforeconsist of a roller chain stretch which operates in an unclosed track.

In this embodiment of the operating mechanism each drive element thusrequires only one sprocket wheel 21 forming the center point of theunclosed track which, by means of the above described straight groove17, extends tangentially to the upper part of the sprocket wheel. On theopposite side there extends, likewise tangentially to the sprocket wheel21, a rectangular tube 22 of sheet-metal which extends along beneath theU-shaped rail 14, 15 parallel to the latter or in a slightly convergingdirection relative thereto and ends under the sliding surface 7 wherethe unclosed track 11, 12 has its two end points. The tube 22 forms aguide in which the lower chain stretch 9', which does not transmit anyforce, can run freely back and forth.

The two sprocket wheels 21 are attached to a transverse drive shaft 23which is the output shaft of a gear transmission 24 that is driven by anelectric motor 25. The transmission can expediently consist of a wormscrew on the motor shaft, arranged vertically and in front of a wormwheel 26 on the drive shaft 23, by which means the motor acquires acentral position at the rear of the assembly with good clearancerelative to the framework H of the forklift truck.

The upper chain stretch 9" which is force-guided by the groove 17 hasits outermost link, which in the conveying position is locatedimmediately in front of the sprocket wheel 21, connected to a slider 27incorporated in the carrier elements 13. The slider, which is shown insection in FIG. 6, has a cross-section which, like the chain links, fitsbetween the four groove walls 19 and 20 and is, as appears from FIG. 3,considerably longer than the height of the groove 17, whereby the slideris guided satisfactorily in the latter. Projecting upward and forwardfrom the slider, is a plate-shaped part 28 which is preferably madeintegral with the slider and is considerably narrower than the latter sothat it fits into the longitudinal slot 29 which opens vertically at thetop of the groove 17 and is located immediately below and parallel tothe sliding surface 5.

Above the sliding surface the plate-shaped parts 28 of the carrierelements are extended forwards so that two similarly positioned andfreely projecting bars are formed. The ends of these are bridginglyconnected by means of a rod-shaped electromagnet 30 which extends atright angles to the grooves 17 and the chain stretches 9", 10" across atleast the central part of the sliding surface 5. The length of the saidbars is such that, when the drive and carrier elements have beendisplaced the length L and assume the fully forward position shown bydot-and-dash lines in FIG. 3, they reach out past the front edge of thesliding surface 5 and onto the press table B to a sufficient extent forthe press tool A, with the magnetic rod 30 as an abutment means, toreach the intended position on the press C.

When this end position of the operating mechanism is assumed and thetool has, by means of the pushing force from the operative chainstretches 9" and 10", been moved forwards along the sliding surface 5,the current to the motor 25 is switched off or changed to an invertedphase sequence under the action of an end position breaker 31. Thelatter can be situated immediately in front of one of the sprocketwheels 21, which position the outer end of the idle stretches 9' and 10'of the chains has now reached, and in such a case the end positionbreaker can suitably be connected in such a way that it reacts when itis passed by the last link of one of the idle chain stretches, on thedrawing the part 10' . In this way the operating mechanism is stoppedor, upon inversion of the phases, returns to the conveying position.

When the press tool A is to be removed from the press, the operatorconnects the electromagnet 30, by means of one of the buttons on theswitch 32, to the forklift truck power supply system, whereafter withthe fork E at the correct level relative to the press table B, he drivesforwards to the press at the same time as he presses another of thebuttons on the switch, which supplies current to the motor 25, so thatthe operating mechanism is allowed to push the carrier to the fullyforward position.

Upon contact between the rod magnet 30 and the press tool A, which isassumed to be of magnetic material, the operator can, by starting up themotor 25 and the drive elements 9, 10 in the opposite direction, pullthe tool, without manual intervention, from the press table andthereafter move it rearward along the sliding surface 5 towards theconveying position. When this position is reached, a second end positionbreaker 33 comes into operation. This breaker can be situated in themovement track of a part of the carrier elements 13, for example one ofthe plate-shaped parts 28, whose rearward edge strikes the breaker 33and stops the movement of the drive and manoeuvring elements and thus ofthe tool A.

In an alternative embodiment (not shown on the drawing) the carriermeans has no electromagnet. Instead the plate-shaped part 18 of eachcarrier element is provided with a gripping means which is directedoutwardly and can be a hook or a similar mechanical element. Each of thegripping means is arranged to interlock with, respectively be releasedfrom, a lug or the like on the tool or the object which is to moved.

It is evident that the length of the carrier elements 13, regardless oftheir design, shall be such that the tool or the object A can be pushedout to a sufficient extent past the front edge of the tines F and of thesliding surface 5 to reach the correct position in question, and can bepulled from said position to a conveying position on the sliding surfaceof the assembly.

From the foregoing it can be seen that an assembly according to theinvention, comprising an operating mechanism which has thecharacteristic features described above and defined by the claims,provides a simple, inexpensive and efficiant apparatus for moving heavyobjects from one to another of a number of supporting positions inindustrial premises.

I claim:
 1. An accessory adapted to be readily removably mounted on theforwardly projecting tines of a forklift truck, by means of which heavyarticles can be slid off of and onto supporting surfaces and on whichsuch articles can be transported from one to another of such surfaces,said accessory comprising:A. structure providing a platform having(1) afront end, (2) a rear end, (3) laterally opposite sides, and (4) topsurface portions which lie in a substantially horizontal plane and uponwhich a heavy article can be slidably supported; B. a laterallyextending shaft confined to rotation near the rear end of said platformand below and parallel to said plane; C. a pair of axially spacedsprockets on said shaft, constrained to rotation with it, each saidsprocket being oriented to have a top and a bottom; D. two track pairson said structure, one track pair for each of said sprockets,(1) eachsaid track pair comprising(a) an elongated upper track having a rear endforwardly adjacent to the top of its sprocket and a front end near thefront end of said platform, and (b) an elongated lower track which isspaced downwardly from the upper track, has a rear end forwardlyadjacent to the bottom of its sprocket, and has a front end between itssprocket and the front end of said platform, and (2) each said trackbeing of substantially U-shaped cross-section and defining an upwardlyopening groove; E. a pair of drive chains, one for each of saidsprockets, each said drive chain having(1) a medial portion trainedaround the rear of its sprocket to be driven lengthwise by rotation ofthe sprocket, (2) an upper stretch which has a front end and which isreceived with a close slidable fit in the upper track for its sprocketto be confined to linear motion by that track, and (3) a lower stretchwhich has a front end and which is similarly received in the lower trackfor its sprocket; F. a pair of sliders, one for each drive chain, eachsaid slider having(1) a lower portion(a) which is confined in the uppertrack for the drive chain, to be constrained by that track to motionlengthwise along it, and (b) which has a connection with the front endof the upper stretch of its drive chain, to be moved along said track byrotation of the sprocket for its chain, and (2) an upper portion whichis above said plane; G. article engaging means secured to the upperportions of said sliders, at front ends thereof, and bridging acrossthem, whereby an article can be slid off of said top surface of theplatform; and H. drive means on said structure for driving said shaft ineach direction of its rotation.
 2. The accessory of claim 1, furthercharacterized in that said drive means comprises:(1) a worm wheel fixedon said laterally extending shaft, between said sprockets, (2) a motormounted on said platform, near the rear end thereof, most of said motorbeing above said plane, and said motor having a vertical motor shaftwhich projects below said plane, and (3) a worm gear on the shaft ofsaid motor, drivingly engaging said worm wheel.
 3. The accessory ofclaim 1, wherein the lower portion of each said slider has front andrear ends, said accessory being further characterized in that:(1) theconnection between the lower portion of each said slider and the upperstretch of its drive chain is at said rear end of said lower portion,and (2) the upper portion of each said slider has a front end which is asubstantial distance forward of said front end of the lower portion andto which said article engaging means is secured.
 4. The accessory ofclaim 1, further characterized by: said structure that provides aplatform further having(1) means on a bottom portion thereof defining apair of channels, one extending fore-and-aft along each of saidlaterally opposite sides, each adapted to receive a tine of a forklifttruck by which the accessory can be supported, and (2) means defining adownwardly projecting protuberance on each such channel, receivable witha substantially close fit in a hole in a forklift truck tine to confinethe accessory against substantially horizontal displacement relative tosaid tines.
 5. An accessory adapted to be readily removably mounted onthe forwardly projecting tines of a forklift truck, by means of whichheavy articles can be slid off of and onto supporting surfaces and onwhich such articles can be transported from one to another of suchsurfaces, said accessory comprising:A. structure that provides aplatform having(1) a front end, (2) a rear end, (3) laterally oppositesides, and (4) top surface portions which lie in a substantiallyhorizontal plane and upon which a heavy article can be slidablysupported; and (5) bottom portions defining a pair of fore-and-aftextending laterally spaced apart channels, in each of which a tine of aforklift truck is receivable for supporting the accessory; B. alaterally extending shaft confined to rotation near the rear end of saidplatform and below and parallel to said plane; C. a pair of axiallyspaced sprockets on said shaft, constrained to rotation with it, eachoriented to have a top and a bottom; D. two track pairs on saidstructure, one track pair for each of said sprockets,(1) each said trackpair comprising(a) an elongated upper track having a rear end forwardlyadjacent to the top of its sprocket and a front end near the front endof said platform, and (b) an elongated lower track which is spaceddownwardly from the upper track, has a rear end forwardly adjacent tothe bottom of its sprocket, and has a front end between its sprocket andthe front end of said platform, and (2) each said track being ofsubstantially U-shaped cross-section and defining an upwardly openinggroove; E. a pair of drive chains, one for each of said sprockets, eachsaid drive chain having(1) a medial portion trained around the rear ofits sprocket to be driven lengthwise by rotation of the sprocket, (2) anupper stretch which has a front end and which is received with a closeslidable fit in the upper track for its sprocket to be confined tolinear motion by that track, and (3) a lower stretch which has a frontend and which is similarly received in the lower track for its sprocket;F. a pair of sliders, one for each drive chain, each said sliderhaving(1) a lower portion which has front and rear ends, said lowerportion(a) being confined in the upper track for the drive chain, to beconstrained by that track to motion lengthwise along it, and (b) havingat its rear end a connection with the front end of the upper stretch ofits drive chain, to be moved along said track by rotation of thesprocket for its chain, and (2) an upper portion which is above saidplane and which has a front end that is a substantial distance forwardof the front end of the lower portion; G. article engaging means securedto said front ends of the upper portions of said sliders and bridgingacross them, whereby an article can be slid off of said top surface ofthe platform and a distance forwardly beyond the front end of theplatform; H. drive means on said structure for driving said shaft ineach direction of its rotation; and I. means defining a downwardlyprojecting protuberance on each said channel, receivable with asubstantially close fit in a hole in a forklift truck tine to confinethe accessory against forward and rearward displacement relative toforklift truck tines on which it is supported.